Health insurance companies will get an extra 16 days to tell District regulators what plans they expect to sell — and how much they will cost — on the new online benefit marketplace now under development.

Health plans originally had until next Wednesday to announce their rates, a closely watched deadline because it's the first time insurers must commit to exactly how the 2010 federal health overhaul law will affect their prices.

Now, they will have until May 31, according to the D.C. Department of Insurance, Securities and Banking.

By then, D.C. Council may have voted on a controversial plan to require small businesses and individuals to buy coverage through the exchange after a two-year transition. The council may consider the plan under emergency legislative rules, multiple city sources have said, fast-tracking a final vote.

However, Council Chairman Phil Mendelson said Friday he is not aware of plans to consider it under emergency rules. That process could enable a vote before the end of the month, but also require nine votes instead of a bare majority on the 13-member Council.

"At the moment, I'm not confident there are nine votes either way, only because I know there's still some debate," Mendelson said.

However, the insurance department appears hopeful an extra 16 days will make the difference. "The resolution of the transition plan is significant to the implementation of the [exchange] for both the carriers and DISB," the statement reads.

The four major insurers now in the city's individual and small-group market — CareFirst BlueCross BlueShield, Kaiser Permanente, Aetna Inc. and UnitedHealthcare — all say they will participate.

"We want to make sure that the carriers have the time they need to file their products and rates for 2014, given their declaration of intent to participate in the exchange," said Richard Sorian, a spokesman for the exchange.

The Council Health Committee will host a roundtable discussion on the exchange Monday at 11 a.m. at the John A. Wilson Building.